The present invention relates to articulated braces of the general type disclosed in U.S. Pat. No. 5,052,379 and which are used on a person's arm or leg to assist flexion and extension of the arm or leg during rehabilitation or health training. Commonly, such a brace includes two pairs of arms which are pivotally connected by corresponding hub components, and each pair of arms is attached by releasable straps to a person's arm or leg with the pivot axis generally aligned with the pivot axis of a joint within the arm or leg. Usually, the hub components of the brace are provided with adjustable or repositionable stop pins which limit the angle of pivotal movement of the brace and the corresponding flexion of the arm or leg.
As disclosed in the above patent, it is sometimes desirable to provide the brace with a resistance to pivotal movement to provide for exercising the arm or leg against a preselected torque or resistance. As disclosed in the above patent in connection with FIGS. 5 and 6, the resistance may be provided by the shear resistance of a viscous fluid which resists rotation of a rotor in opposite directions within a housing. The resistance is varied by changing the viscosity of the fluid or by changing the clearance space between the rotor and the surrounding housing.
It has been found desirable for an articulated brace to provide for conveniently selecting between no resistance and a predetermined resistance depending upon the purpose for which the brace is used. It has also been found desirable for the brace to provide for conveniently adjusting the resistance to flexion of the brace and the resistance to extension of the brace. Furthermore, it is desirable for the brace to provide for selecting or varying the resistance to flexion or extension and independently of each other.